When your venue is given a counterfeit note, you should contact your local police or the Australian Federal Police in your state/territory. You should also complete a Suspect counterfeit banknote form detailing the circumstances of how you came into possession of the counterfeit to assist police.
If there is no police involvement you should send the suspected counterfeit, together with a completed Suspect counterfeit banknote form via registered mail to:
Australian Federal Police
Locked Bag 4817
Somerton VIC 3062
A property receipt will be forwarded to you acknowledging receipt of the property.